Angiotensin-converting enzyme (ACE) activity in serum and insertion/deletion (I/D) polymorphism have been associated to cardiovascular disease in several studies. Objective. To find a relationship between ACE activity and I/D polymorphism in the enzyme gene in patients with coronary obstruction revealed by angiography. Materials and methods. Sample comprised patients attending a hemodynamics center in Quindío in need of a coronary angiography. ACE activity was measured by electrophotometry and the I/D genotype determined by polymerase chain reaction. Results. 542 patients were divided into two groups: individuals with coronary obstruction higher than or equal to 50% (OC≥50) and individuals with coronary obstruction less than 50% (CO<50%). Serum ACE activity in the global population was higher in individuals with DD polymorphism, followed by ID and II with significant differences. A similar pattern was shown in both study groups but without significant differences, although enzyme activity was always higher in individuals with OC≥50% compared with patients with OC<50%. ID genotype was the most frequent in both groups. No differences were found in allele and genotype frequencies in the study groups. Conclusions. Significant differences in ACE activity were found
according to genotype. Our study did not find any relationship between ACE activity, I/D polymorphisms and coronary obstruction.

Key words: angiotensin-converting enzyme, coronary obstruction, ID polymorphism, angiotensin.